Get the size you want--
head to foot, side to side,
in MED

Then use this code in the model's action:
Code:

---

            vec_set(my.min_x, vector (-22,-22,-35));     //x,y,z minimums
	vec_set(my.max_x, vector(44,44,35));     //x,y,z maximums
	my.narrow = on;
	my.fat = on;  

---

According to the manual my.narrow and my.fat have to be there.